1. DO NOW 1. Grab Weekly 2. Grab Chapter 12 Packet

2. Ch. 12 History of Life on Earth

3. How did Life Begin? Age of Earth
billion years ago Earth was a fiery ball of rock
2. Surface of Earth cooled
3. Water vapor in air condensed to form ocean water where life first evolved
Age of Earth

4. How did Life Begin? Measuring the Age of Earth
Scientist have measured the age of the rocks found on Earth using radiometric dating
The age of the rock is measured based on how much it has broken down throughout the years called radioactive decay

5. How did Life Begin? Measuring the Age of Earth
Radioactive Decay of a rock’s content of certain “isotopes” is measured in Half-Lives
Half Life
Time it takes for one half of a certain amount of radioisotope to decay
By measuring this, scientists can calculate how many half lives have passed since a rock was formed
Measuring the Age of Earth

6. How did Life Begin? Measuring the Age of Earth
Isotopes breakdown in half lives

7. The Theories – How Life Began
Nonliving matter was energized by sun and volcanic heat
Caused chemical reaction to produce simple organic molecules
Organics became more complex
First cells developed
1. Formation of Life’s Chemicals

8. The Theories – How Life Began
Hypothesized that Earth’s oceans were once filled with organic molecules (“soup”)
But, there was no oxygen in the air: only nitrogen, hydrogen, water, ammonia, methane
Primordial Soup Model

9. The Theories – How Life Began
Solar radiation, volcanic eruptions, lightning excited electrons in gases
Electrons reacted with Hydrogen in the air to form organic molecules
This hypothesis was actually tested and SUPPORTED!
Primordial Soup Model

10. Results – found a complex collection of organic molecules
Results – found a complex collection of organic molecules! Compounds included life’s building blocks – amino acids, fatty acids – Hypothesis Supported!

11. The Theories – How Life Began
Scientists Louis Lerman hypothesized that the key processes that formed the chemicals needed for life took place within bubbles on the oceans surface
The bubbles contained the gases needed to make organic molecules
Chemical reactions took place inside the bubbles and UV radiation made this process occur quickly
Lerman suggested this theory occurred much more quickly than the Primordial Soup Model
Bubble Model

12. Whiteboard – Quick Questions
According to scientists how old is the Earth?
After three half-lives of a radioisotope have passed, how much of the original isotope is undecayed?
1/8 (2) ¾ (3) ½ (4) 7/8
What is “Primordial Soup”?

13. When did the 1st Organisms Form?
Evolution of Pro-karyotes
The best evidence we have to study early life are fossils
Fossil- preserved remains (bone, tooth, shell) or imprint of an organism from long ago

14. How did Life Begin?
Evolution of Pro-karyotes
Oldest fossils - photosynthetic prokaryotes (cyanobacteria)
2.5 billion years old
Released oxygen into oceans
Oxygen eventually escaped into air as more and more was produced

15. Quick Check - Prokaryotes
Evolution of Pro-karyotes
Hold up 1 finger if prokaryotes do have a nucleus
Hold up 2 fingers if they do not
Hold up 1 finger if they are unicellular
Hold up 2 fingers if they are multicellular

16. Two Groups of Prokaryotes
Evolution of Pro-karyotes
Eubacteria
Cell walls contain peptidoglycan
Cause disease and decay
Ex: E.Coli
Archaebacteria
Cell walls lack peptidoglycan
Unique lipid cell membranes
The 1st eukaryotic cells evolved from archaebacteria

17. The Evolution of Eukaryotes
About 1.5 million years ago the first eukaryotes appeared
With your shoulder partner try to come up with 3 characteristics of Eukaryotes
Eukaryotes
Larger
More Complex
Internal Membranes
DNA in a nucleus
Mitochondria
Chloroplasts

18. The Kingdoms Evolution of Eu-karyotes
Biologist group all living things into six kingdoms.
The first two kingdoms are Eubacteria and Archaebacteria
TRY THIS
Name the other four kingdoms
Circle the kingdom you believe came first before all the rest
Protists – Fungi – Plants - Animals

19. The 1st Eukaryotes The first Eukaryotic Kingdom were Protists
Includes both multi and unicellular organisms
Single celled organisms STILL carry out all of activities for life’s processes (ex: metabolism, homeostasis)
Multicellular protists include Algae

20. Extinction Mass Extinctions
Extinction- Death of all members of a species
Mass Extinction- Episode during which large numbers of species become extinct
The fossil records show large percentages of the Earth’s organisms were becoming extinct
A total of 5 have occurred

21. Extinction Mass Extinctions Most devastating- end of Permian period
245 million years ago
96% of all species became extinct
Cause may have been worldwide geological and weather changes

22. How did Life Begin? Mass Extinctions Fifth mass extinction
2/3 of all land species (including dinosaurs) become extinct

23. Extinction Mass Extinctions A sixth mass extinction event?
May be currently occurring due to destruction of tropical rain forests by human activity
Can you name the most recent extinction or a species?
Western Black Rhino

24. The Ozone Layer Ozone Layer
Life began in the oceans, why did life suddenly form on land?
UV radiation from the sun is harmful
As cyanobacteria began supplying the air with oxygen, chemical reactions in the atmosphere created the ozone
The Ozone layer blocked the UV radiation and made the Earth’s land a safe place to live

26. Whiteboard – Quick Questions
Name the kingdom that includes single and multicellular organisms
Yes or No would today’s organisms exist if the mass extinctions did not occur? Think – Why or why not
How did cyanobacteria contribute to the beginning of more complex life on Earth?
Western Black Rhino

27. Do Now Grab a textbook Turn in Chapter 11 Take home Exam
p. 8 Wednesday DoNow
**Don’t forget – Weekly Due Friday
Western Black Rhino

28. Section 3 – Gallery Walk
Each group will be assigned a section from Pages 265 – 268
Make a poster of your section in 15 minutes
Make sure you can answer your questions
We will walk around to each groups poster and have 5 minutes to review and discuss each
Western Black Rhino

29. Section 3 – Gallery Walk
Each group will be assigned a section from Pages 265 – 268
Sections:
Plants & Fungi on Land – p.265
Arthropods – p. 266
Fish – p.267
Amphibians – p.267
Reptiles – p.268
Mammals & Birds – p.268
Western Black Rhino

30. Section 3 – Gallery Walk Each group will be assigned a section
Make a poster of your section in 15 minutes
Make sure you can answer your questions
We will walk around to each groups poster and have 5 minutes to review and discuss each
Western Black Rhino

31. How did Life Begin? Plants and Fungi on Land
Plants evolved from photo. bacteria
Use sunlight to generate nutrients
Cannot harvest materials from bare rock

32. How did Life Begin? Plants and Fungi on Land Fungi
Can harvest materials from bare rock
Cannot use sunlight to generate nutrients

33. How did Life Begin? Plants and Fungi on Land
Together, they form a mutualistic relationship (both benefit)
Mycorrhizae- fungus provides minerals to plant, and plant provides nutrients to fungi

34. How did Life Begin? Arthropods
First animals to successfully invade land (first most likely scorpion)
Hard, outer skeleton
Segmented body
Paired, jointed limbs
Lobsters, crabs, insects, spiders

35. How did Life Begin? Arthropods Insects
Most plentiful, diverse group on Earth
First to have wings and fly
Efficient at searching for food, mates and nesting sites

36. How did Life Begin? Vertebrates (animals with a backbone) A. Fishes
First vertebrates- small jawless fishes
Jawed fish evolved- allowed predation
Most successful of living vertebrates
Developed into land dwellers

37. How did Life Begin? Vertebrates (animals with a backbone)
B. Amphibians
First land vertebrates (to come out of sea)
Smooth skinned, four legged
Frogs, toads, salamanders
Developed lungs for absorbing oxygen from air
Limbs derived from bones in fish fins
Strong, flexible internal skeleton for walking
Lay eggs in moist areas

38. How did Life Begin? Vertebrates (animals with a backbone) C. Reptiles
Evolved from amphibians
Snakes, lizards, turtles, crocodiles
Watertight skin locks moisture in while living on land
Can lay eggs on dry land

39. How did Life Begin? Vertebrates (animals with a backbone)
D. Mammals and Birds
Evolved from reptiles
5th mass extinction: only dinosaurs that were ancestors to birds, small reptiles and small mammals survived

40. How did Life Begin? Continental Drift
Movement of land masses over Earth’s surface through geologic time
Explains why there are Marsupials in both Australia and South America although they are extremely far apart

42. WEBSITES
ajkf

43. Assessment Three
Summarize how ozone was important in enabling organisms to live on land
Name the first multicellular organisms that colonized land
Identify the first kinds of animals to live on land
Describe the first kinds of vertebrates that inhabited land
Defend the argument that invasion of land could not have happened until well after the evolution of cyanobacteria
Mycorrhizae are mutualistic relationships between the roots of plants and what other type of organisms?